MICROBIOLOGICAL PROCESSES IN MARINE-SEDIMENTS IN THE ZAIRE RIVER-DELTA AND THE BENGUELA UPWELLING REGION

Microbiological processes in marine sediments in the zone of influence of the Zaire River discharge (6 degrees S) and in the Benguela upwell ing area (17 degrees, 23 degrees, 25 degrees) were studied. Microbiolo gical and biogeochemical investigations demonstrated that the Zaire Ri ver influences a vast area in coastal and deep-sea regions down to the bottom of the continental slope. In reduced shelf sediments, active p rocesses of anaerobic organic matter decomposition were revealed. The rates of glucose utilization were 3300 mu g C/kg/day in the sediments of the Zaire River estuary and 4400 mu g C/kg/day in the shelf sedimen ts of Benguela upwelling. In both studied areas active processes of me thanogenesis and sulfate reduction were demonstrated. Comparative eval uation of organic carbon fluxes for sulfate reduction and methanogenes is indicated that organic matter decomposition in the Zaire River estu ary was mediated mainly by sulfate reduction. In the sediments of the Benguela shelf both methanogenesis and sulfate reduction were equally represented. Pure cultures of methanogenic bacteria utilizing methanol and methylamines were isolated from sediments in the Benguela upwelli ng area.